1. Field of the Invention
The present invention relates to a detection system of obstacles for use in vehicles, wherein various information data concerning each target existing on a course to be traveled by the vehicle, such as size or dimension of each target, a direction of each target to the vehicle, a distance between the vehicle and each target, mutual distance of targets facing each other, and a height of each target lying over the vehicular course, are detected by using a laser light, and from said information as detected decisions are enabled as to possibilities of accidents such as collision, contacts, etc. of the vehicle with each of the targets on the course.
Upon driving the vehicle it is necessary for a driver to make decisions of various possibilities; such as the possibility of collision with targets which may be, for example, preceding vehicles located ahead of the vehicle; the possibility of passing-through a space between vehicles parked or stopped along side portions of the road, etc; the possibility of passing-through under targets located above the vehicle such as arcades, overbridges for pedestrian, and the like.
The decisions described above may be realized to some extent by a driver having extensive driving experience. However, such personal decisions are insufficient for the purposes of complete safety in the driving operation. Thus, it is required to provide the driver with auxiliary means through which he can make properly said decisions so that driving safety is ensured, contributing to substantial reduction of accidents by vehicles such as automobiles.
2. Description of the Prior Art
The various decisions recited above have previously been effected by an eye measurement of the driver. Such decisions however, are insufficient.
Heretofore, systems for decision as to possibility of collision with targets ahead of the vehicle have been proposed, wherein a radio radar is mounted on the vehicle and the distance to the targets from the vehicle and/or the relative speed of the targets to the vehicle are detected. However, in the radio radar even a minimum spread angle of the radio beam amounts to the order of about 1.degree. (17 m radians) by limitation in size of the antenna which can be mounted on the vehicle, so that the spot size of the radio beam is caused to spread to a diameter in the order of 85 cm at a location which is 50 m distant from the front portion of the vehicle. Therefore, the known systems present problems in that accurate measurement of the distance and relation in position between the target and the vehicle is difficult; that targets which exist alongside the road and do not form any obstacle, such as guardrails, may be detected erroneously as obstacles; and that any detection systems of obstacles which require very high precision, such as those making the decision as to said possibilities of collision and passing-through cannot be realized.
Moreover, the known detection system using the radio radar has disadvantages that erroneous operation is liable to occur at curved portions of the rod, whereas the known detection system which is provided with a mirror as deflection means of a laser beam cannot achieve precise control of deflection angles for scanning the laser beam.
In addition, the known detection system cannot provide the needed decisions quickly and accurately.